The present invention relates to a reversible four-way valve used in a cooler/heater type air conditioner for switchover operation between an indoor cooling mode and an indoor heating mode.
The conventional pressure differential drive type reversible four-way valve includes a cylindrical valve body, a pair of pistons provided therein to divide said valve body for the most part into three chambers such as a high pressure chamber, a low pressure chamber and a pressure control chamber or a combination of a high pressure chamber and two pressure control chambers. In such conventional four-way valve, pressure in said pressure control chamber is reversibly controlled by a three-way electro-magnetic pilot valve to operate the pistons and the selector valve connected thereto.
The above prior art has a drawback that the structures of the reversible valve body and the pilot body are complicated, involving numerous communication conduits that forestall miniturization. Another drawback includes that the control by means of the electromagnetic pilot valve is intended for the negative decompression and positive compression of the pressure control chamber which is not suited for a delicate electromagnetic control.
The inventor took, the above mentioned drawbacks into consideration to come up with an idea of dividing the valve body by a single piston into two chambers including a high pressure chamber and a pressure control chamber while controlling the pressure control chamber by a pilot valve to move the piston and the slide valve connected thereto. As a result, simplification and miniturization of the structure has been attained while enabling a delicate electromagnetic control. Moreover, delicate electromagnetic control by means of sensitive electromagnetic means can now be used because the control of the pressure control chamber is performed by controlling a one-way refrigerant flow from the pressure control chamber to the compresser.